Method and apparatus for attaching a reference marker to a patient

ABSTRACT

Systems and methods for attaching a reference marker to a patient in a computer-assisted image-guided surgery system. An apparatus for attaching a reference marker to a patient includes an elongated member extending between a first end and a second end, a sharp tip located proximate to the first end of the elongated member that is configured to break through a cortical surface of a bone of the patient to enable the elongated member to be advanced into the bone, an anchoring device that is extendable from the elongated member in order to anchor the apparatus within the bone and inhibit relative movement of the apparatus and the bone, and a reference marker device comprising at least one optical marker configured to enable the apparatus to be tracked using a motion tracking system.

BACKGROUND

Computer-assisted surgical procedures, which may include image guidedsurgery and robotic surgery, have attracted increased interest in recentyears. These procedures include the integration of a “virtual”three-dimensional dataset of the patient's anatomy, typically obtainedusing pre-operative or intra-operative medical imaging (e.g., x-raycomputed tomography (CT) or magnetic resonance (MR) imaging), to theactual position of the patient and/or other objects (e.g., surgicalinstruments, robotic manipulator(s) or end effector(s) in the surgicalarea. These procedures may be used to aid the surgeon in planning asurgical procedure and may also provide the surgeon with relevantfeedback during the course of surgical procedure. There is a continuingneed to improve the safety and ease-of-use of computer-assisted surgicalsystems.

SUMMARY

Various embodiments include systems and methods for attaching areference marker to a patient in a computer-assisted image-guidedsurgery system.

Embodiments include an apparatus for attaching a reference marker to apatient includes an elongated member extending between a first end and asecond end, a sharp tip located proximate to the first end of theelongated member that is configured to break through a cortical surfaceof a bone of the patient to enable the elongated member to be advancedinto the bone, an anchoring device that is extendable from the elongatedmember in order to anchor the apparatus within the bone and inhibitrelative movement of the apparatus and the bone, and a reference markerdevice comprising at least one optical marker configured to enable theapparatus to be tracked using a motion tracking system.

Further embodiments include a method of performing image guided surgerythat includes inserting an apparatus comprising an elongated memberhaving a sharp tip at an end of the elongated member into the body of apatient to cause the sharp tip to break through a cortical surface of abone of the patient, anchoring the apparatus within the bone to inhibitrelative movement of the apparatus and the bone, and tracking areference marker device having at least one optical marker attached tothe apparatus using a motion tracking system.

Further embodiments include a system for performing image guided surgeryusing an apparatus for attaching a reference marker to a patient.

BRIEF DESCRIPTION OF THE DRAWINGS

Other features and advantages of the present invention will be apparentfrom the following detailed description of the invention, taken inconjunction with the accompanying drawings of which:

FIG. 1 is a perspective view of a system for performingrobotically-assisted image-guided surgery.

FIGS. 2A-2D illustrate a first embodiment apparatus for attaching areference marker to a patient.

FIGS. 3A-3C schematically illustrate an embodiment apparatus embeddedwithin a bone of a patient.

FIG. 4 illustrates a second embodiment apparatus for attaching areference marker to a patient.

FIG. 5 illustrates an embodiment system for performing image guidedsurgery that includes a plurality of reference markers fixed to apatient.

FIG. 6 illustrates another embodiment system for performing image guidedsurgery that includes a plurality of reference markers fixed to apatient

FIG. 7 illustrates yet another embodiment system for performing imageguided surgery that includes a first reference marker fixed to a bone ofa patient and a plurality of optical markers fixed over the skin surfaceof the patient.

DETAILED DESCRIPTION

The various embodiments will be described in detail with reference tothe accompanying drawings. Wherever possible, the same reference numberswill be used throughout the drawings to refer to the same or like parts.References made to particular examples and implementations are forillustrative purposes, and are not intended to limit the scope of theinvention or the claims.

FIG. 1 illustrates a system 100 for performing computer-assistedimage-guided surgery according to various embodiments. The system 100 inthis embodiment includes an imaging device 103, a motion tracking system105 and a robotic arm 101 for performing a robotically-assisted surgicalprocedure. The robotic arm 101 may comprise a multi joint arm thatincludes a plurality of linkages connected by joints having actuator(s)and optional encoder(s) to enable the linkages to rotate, bend and/ortranslate relative to one another in response to control signals from arobot control system. The robotic arm 101 may be fixed to a supportstructure at one end and may have an end effector 102 at the other endof the robotic arm 101.

The imaging device 103 may be used to obtain diagnostic images of apatient (not shown in FIG. 1), which may be a human or animal patient.In embodiments, the imaging device 103 may be an x-ray computedtomography (CT) imaging device. The patient may be positioned within acentral bore 107 of the imaging device 103 and an x-ray source anddetector may be rotated around the bore 107 to obtain x-ray image data(e.g., raw x-ray projection data) of the patient. The collected imagedata may be processed using a suitable processor (e.g., computer) toperform a three-dimensional reconstruction of the object. In otherembodiments, the imaging device 103 may comprise one or more of an x-rayfluoroscopic imaging device, a magnetic resonance (MR) imaging device, apositron emission tomography (PET) imaging device, a single-photonemission computed tomography (SPECT), or an ultrasound imaging device.In embodiments, image data may be obtained pre-operatively (i.e., priorto performing a surgical procedure), intra-operatively (i.e., during asurgical procedure) or post-operatively (i.e., following a surgicalprocedure) by positioning the patient within the bore 107 of the imagingdevice 103. In the system 100 of FIG. 1, this may be accomplished bymoving the imaging device 103 over the patient to perform a scan whilethe patient may remain stationary.

Examples of x-ray CT imaging devices that may be used according tovarious embodiments are described in, for example, U.S. Pat. No.8,118,488, U.S. Patent Application Publication No. 2014/0139215, U.S.Patent Application Publication No. 2014/0003572, U.S. Patent ApplicationPublication No. 2014/0265182 and U.S. Patent Application Publication No.2014/0275953, the entire contents of all of which are incorporatedherein by reference. In the embodiment shown in FIG. 1, the patientsupport 60 (e.g., surgical table) upon which the patient may be locatedis secured to the imaging device 103, such as via a column 50 which ismounted to a base 20 of the imaging device 103. A portion of the imagingdevice 103 (e.g., an O-shaped imaging gantry 40) which includes at leastone imaging component may translate along the length of the base 20 onrails 23 to perform an imaging scan of the patient, and may translateaway from the patient to an out-of-the-way positon for performing asurgical procedure on the patient.

An example imaging device 103 that may be used in various embodiments isthe AIRO® intra-operative CT system manufactured by Mobius Imaging, LLCand distributed by Brainlab, AG. Other imaging devices may also beutilized. For example, the imaging device 103 may be a mobile CT devicethat is not attached to the patient support 60 and may be wheeled orotherwise moved over the patient and the support 60 to perform a scan.Examples of mobile CT devices include the BodyTom® CT scanner fromSamsung Electronics Co., Ltd. and the O-Arm® surgical imaging systemform Medtronic, plc. The imaging device 103 may also be a C-arm x-rayfluoroscopy device. In other embodiments, the imaging device 103 may bea fixed-bore imaging device, and the patient may be moved into the boreof the device, either on a surgical support 60 as shown in FIG. 1, or ona separate patient table that is configured to slide in and out of thebore. Further, although the imaging device 103 shown in FIG. 1 islocated close to the patient within the surgical theater, the imagingdevice 103 may be located remote from the surgical theater, such as inanother room or building (e.g., in a hospital radiology department).

The motion tracking system 105 shown in FIG. 1 includes a plurality ofmarker devices 119, 202 and an optical sensor device 111. Varioussystems and technologies exist for tracking the position (includinglocation and/or orientation) of objects as they move within athree-dimensional space. Such systems may include a plurality of activeor passive markers fixed to the object(s) to be tracked and a sensingdevice that detects radiation emitted by or reflected from the markers.A 3D model of the space may be constructed in software based on thesignals detected by the sensing device.

The motion tracking system 105 in the embodiment of FIG. 1 includes aplurality of marker devices 119, 202 and a stereoscopic optical sensordevice 111 that includes two or more cameras 206 (e.g., IR cameras). Theoptical sensor device 111 may include one or more radiation sources(e.g., diode ring(s)) that direct radiation (e.g., IR radiation) intothe surgical field, where the radiation may be reflected by the markerdevices 119, 202 and received by the cameras. The marker devices 119,202 may each include three or more (e.g., four) reflecting spheres,which the motion tracking system 105 may use to construct a coordinatesystem for each of the marker devices 119, 202. A computer 113 may becoupled to the sensor device 111 and may determine the transformationsbetween each of the marker devices 119, 202 and the cameras using, forexample, triangulation techniques. A 3D model of the surgical space in acommon coordinate system may be generated and continually updated usingmotion tracking software implemented by the computer 113. Inembodiments, the computer 113 may also receive image data from theimaging device 103 and may register the image data to the commoncoordinate system as the motion tracking system 105 using imageregistration techniques as are known in the art.

In embodiments, at least one reference marker device may be attached tothe patient, as described further below. The patient reference markerdevice may be rigidly attached to a landmark in the anatomical region ofinterest (e.g., clamped or otherwise attached to a bony portion of thepatient's anatomy) to enable the anatomical region of interest to becontinually tracked by the motion tracking system 105. The patientreference marker device may be used to define the common, patient-basedcoordinate system during the procedure. Additional marker devices 119may be attached to surgical tools or instruments 104 to enable thetools/instruments 104 to be tracked within the common coordinate system.Another marker device 202 may be rigidly attached to the robotic arm101, such as on the end effector 102 of the robotic arm 101, to enablethe position of robotic arm 101 and end effector 102 to be tracked usingthe motion tracking system 105. The computer 113 may also includesoftware configured to perform a transform between the joint coordinatesof the robotic arm 101 and the common coordinate system of the motiontracking system 105, which may enable the position and orientation ofthe end effector 102 of the robotic arm 101 to be controlled withrespect to the patient 200.

In addition to passive marker devices described above, the motiontracking system 105 may alternately utilize active marker devices thatmay include radiation emitters (e.g., LEDs) that may emit radiation thatis detected by an optical sensor device 111. Each active marker deviceor sets of active marker devices attached to a particular object mayemit radiation in a pre-determined strobe pattern (e.g., with modulatedpulse width, pulse rate, time slot and/or amplitude) and/or wavelengthwhich may enable different objects to be uniquely identified and trackedby the motion tracking system 105. One or more active marker devices maybe fixed relative to the patient, such as secured to the patient's skinvia an adhesive membrane or mask. Additional active marker devices maybe fixed to surgical tools 104 and/or to the end effector 102 of therobotic arm 101 to allow these objects to be tracked relative to thepatient.

In further embodiments, the marker devices may be passive maker devicesthat include moiré patterns that may enable their position andorientation to be tracked in three-dimensional space using a singlecamera using Moiré Phase Tracking (MPT) technology. Each moiré patternmarker may also include a unique identifier or code that may enabledifferent objects within the camera's field of view to be uniquelyidentified and tracked. Other tracking technologies, such as computervision systems and/or magnetic-based tracking systems, may also beutilized.

As shown in FIG. 1, the optical sensor device 111 may include aplurality of cameras 206 mounted to an arm 208 extending above thepatient surgical area. The arm 208 may be mounted to or above theimaging device 103. The arm 208 may enable the sensor device 111 topivot with respect to the arm 208 and/or the imaging device 103 (e.g.,via one or more ball joints 212). The arm 208 may enable a user toadjust the position and/or orientation of the sensor device 111 toprovide the cameras 206 with a clear view into the surgical field whileavoiding obstructions. The arm 208 may enable the position and/ororientation of the sensor device 111 to be adjusted and then locked inplace during an imaging scan or surgical procedure.

The system 100 may also include at least one display device 120 asillustrated in FIG. 1. The display device 120 may display image data ofthe patient's anatomy obtained by the imaging device 103. In the case ofCT image data, for example, the display device 120 may display athree-dimensional volume rendering of a portion of the patient's anatomyand/or may display two-dimensional slices (e.g., axial, sagittal and/orcoronal slices) through the 3D CT reconstruction dataset. The displaydevice 120 may facilitate planning for a surgical procedure, such as byenabling a surgeon to define one or more target positions in thepatient's body and/or a path or trajectory into the patient's body forinserting surgical tool(s) to reach a target position while minimizingdamage to other tissue or organs of the patient. The position and/ororientation of one or more objects tracked by the motion tracking system105 may be shown on the display 120, and may be shown overlaying theimage data. The use of tracked surgical instruments or tools incombination with pre-operative or intra-operative images of thepatient's anatomy in order to guide a surgical procedure may be referredto as “image-guided surgery.”

In embodiments, the display device 120 may be a handheld display device,such as a tablet computer device. One or more handheld display devices120 may be mounted to an arm 208 extending above the patient surgicalarea, as shown in FIG. 1. The arm 208 may also support the opticalsensing device 111 for the motion tracking system 105, as describedabove. The one or more display devices 120 may be suspended from the arm208, and the position of a display device 120 may be adjustable alongthe length of the arm 208. In other embodiments, a handheld displaydevice 120 may be mounted to the patient support 60 or column 50 or toany portion of the imaging system 103, or to any of the wall, ceiling orfloor in the operating room, or to a separate cart. Alternately or inaddition, the at least one display device 120 may be a monitor displaythat may be located on a mobile cart or mounted to another structure(e.g., a wall) within the surgical theater.

As shown in FIG. 1, the robotic arm 101 may be fixed to the imagingdevice 103, such as on a support element 214 (e.g., a curved rail) thatmay extend concentrically over the outer surface of the O-shaped gantry40 of the imaging device 103. In embodiments, an arm 208 to which theoptical sensing device 111 is mounted may be mounted to the same or asimilar support element 214 (e.g., curved rail) as the robotic arm 101.The position of the robotic arm 101 and/or the arm 208 may be adjustablealong the length of the support element 214. In other embodiments, therobotic arm 101 may be secured to any other portion of the imagingdevice 103, such as directly mounted to the gantry 40. Alternatively,the robotic arm 101 may be mounted to the patient support 60 or column50, to any of the wall, ceiling or floor in the operating room, or to aseparate cart. In further embodiments, the robotic arm 101 and/or theoptical sensing device 111 may be mounted to a separate mobile shuttle,as described in U.S. Provisional Application No. 62/395,443, filed onSep. 16, 2016, which is incorporated by reference herein. Although asingle robotic arm 101 is shown in FIG. 1, it will be understood thattwo or more robotic arms 101 may be utilized. In addition, variousembodiments of a computer-assisted surgical method or system may includeimage-guided or navigation-supported surgery without the use of arobotic arm 101.

The at least one robotic arm 101 may aid in the performance of asurgical procedure, such as a minimally-invasive spinal surgicalprocedure or various other types of orthopedic, neurological,cardiothoracic and general surgical procedures. In embodiments, themotion tracking system 105 may track the position of the robotic arm 101(e.g., via marker device 202 on end effector 102 as shown in FIG. 1)within the patient coordinate system. A control loop may continuouslyread the tracking data and the current parameters (e.g., jointparameters) of the robotic arm 101 and may send instructions to arobotic controller to cause the robotic arm 101 to move to a desiredposition and orientation within the patient coordinate system.

In embodiments, a surgeon may use an image-guided surgery system as aplanning tool for a surgical procedure, such as by setting trajectorieswithin the patient for inserting surgical tools, as well as by selectingone or more target locations for a surgical intervention within thepatient's body. The trajectories and/or target locations set by thesurgeon may be saved (e.g., in a memory of a computer device, such ascomputer device 113 shown in FIG. 1) for later use during surgery. Inembodiments, the surgeon may be able to select stored trajectoriesand/or target locations using an image guided surgery system, and therobotic arm 101 may be controlled to perform a particular movement basedon the selected trajectory and/or target location. For example, therobotic arm 101 may be moved to position the end effector 102 of therobotic arm 101 into alignment with the pre-defined trajectory and/orover the pre-determined target location. The end effector 102 mayinclude a hollow tube or cannula which may be used to guide aninstrument 104 into the patient's body along the pre-defined trajectoryand/or to the pre-defined target location. Alternately, the end effector102 itself may be or may include an instrument that may be inserted intothe patient's body and guided along the pre-defined trajectory and/or tothe pre-defined target location.

Various embodiments include methods and systems for attaching areference marker to a patient in a computer-assisted image-guidedsurgery system. As discussed above, a reference marker device (e.g.,reference arc) may be rigidly attached to a landmark in the anatomicalregion of interest (e.g., clamped or otherwise attached to a bonyportion of the patient's anatomy) to enable the anatomical region ofinterest to be continually tracked by the motion tracking system 105.During an image guided surgical procedure, the diagnostic imaging dataof the relevant anatomy may be registered to a patient coordinate systembased on the position and orientation of the reference marker device115, which may be continually tracked by the motion tracking system 105.The registration may become inaccurate, however, if a marker device isnot rigidly fixed to the patient and/or is accidentally bumped causingit to change its position relative to the patient during a surgicalprocedure. In some situations, the surgeon may not be aware that themarker device has moved relative to the patient and that the imageregistration is no longer accurate.

A first embodiment of an apparatus 200 for attaching a reference markerto a patient is shown in FIGS. 2A-2D. The apparatus 200 includes anouter cannula 201 with a hollow interior 203. An elongated member 205having a sharp tip end 207 may be insertable within the outer cannula201. FIG. 2A illustrates the elongated member 205 outside of the outercannula 201 and FIG. 2B illustrates the elongated member 205 insertedwithin the outer cannula 201. When the elongated member 205 is insertedin the outer cannula 201 as shown in FIG. 2B, the sharp tip end 207 mayproject beyond a first end 209 (e.g., tip end) of the cannula 201. Thesharp tip end 207 may be a cortical perforator that is configured tobreak through the cortical surface of a bone to enable the apparatus 200to be advanced into the bone. The elongated member 205 may be attachedto the outer cannula 201 when it is inserted, such as via a threadedconnector at the second ends 211, 213 of the cannula 201 and theelongated member 205. As shown in FIGS. 2A-2B, the elongated member 205may optionally include a handle 215 (e.g., a t-handle) at the second end213 of the elongated member 205. The apparatus as shown in FIG. 2B maybe inserted into a patient such that the tip end of the apparatus passesthrough the patient's skin and punctures the outer cortical surface of abone. After puncturing the cortical surface, the elongated member 205may optionally be disengaged from the outer cannula 201 (e.g., via thethreaded connector) and may be removed from the outer cannula 201. Theouter cannula 201 may be advanced further into the interior portion ofthe bone. The outer cannula 201 may include a flange 217 or otherfeature (e.g., a t-handle) to enable the user to grip and push the outercannula 201 into the bone.

In some embodiments, the apparatus 200 may be a biopsy needle, includinga bone marrow biopsy needle (e.g., a Jamshidi™ needle). The apparatus200 may optionally be used to harvest tissue from the patient, and inparticular may be used to harvest bone marrow from the patient. Theobtained bone marrow cells may be used to promote bone growth in aspinal fusion or other surgical treatment of the patient. In oneexample, the outer cannula 201 may be pushed into the interior portionof the bone containing the marrow while optionally rotating the outercannula 201 in order to collect the marrow within the hollow interior203 of the cannula 201. The sample (e.g., core) containing the marrowmay then be removed from the outer cannula 201, such as by aspiration orby inserting a separate instrument (e.g., a marrow acquisition cradle)into the cannula 201 to collect the sample.

In various embodiments, the apparatus 200 shown in FIGS. 2A-2B may beinserted into the iliac crest of the patient. This is schematicallyillustrated in FIGS. 3A-3B, which are anterior and lateral views showingan outer cannula 201 of an embodiment apparatus 200 embedded within theiliac crest 301 of a patient. It will be understood that the apparatus200 may be inserted into another bone or skeletal structure of apatient. In general, the apparatus 200 may be inserted into a structurethat is relatively proximate (e.g., less than about 1 meter) from a siterequiring surgical intervention.

The apparatus 200 also includes a marker device 219 that may be fixed tothe outer cannula 201. In one embodiment, as shown in FIG. 2C, themarker device 219 may include a plurality of optical markers 221 (e.g.,reflective spheres) arrayed on a rigid-frame 223. The optical markers221 may be arranged in a unique pattern on the frame 223 to enable thearray of markers 221 to be identified and tracked by a motion trackingsystem 105 as described above with reference to FIG. 1. The frame 223may be attached to an elongated member 225 that may be sized and shapedto be inserted into the outer cannula 201. FIG. 2D illustrates themarker device 219 with the elongated member 225 inserted into the outercannula 201. The marker device 219 may be locked to the cannula 201using a suitable attachment mechanism, such as a threaded connector, alatch mechanism, a locking collar, a snap-fit connector, aninterference-fit, etc. FIG. 3C illustrates the marker device 219 beinginserted into an outer cannula 201 that is partially embedded within thebone 301 of a patient.

The apparatus may optionally also include an anchoring device 227 thatprevents the apparatus 200 from moving relative to patient, includingrotational movement of the apparatus 200 about the central axis of theouter cannula 201. The anchoring device 227 may include a plurality ofelements that may extend from the outer cannula 201 to fix the apparatus200 within the surrounding bone structure. In embodiments, the anchoringdevice 227 may be selectively deployed after the outer cannula 201 is ata desired position within the bone of the patient. For example, theanchoring device 227 may be deployed by extending a plurality ofanchoring elements radially outward with respect to the outer surface ofthe cannula 201 and/or longitudinally away from the tip end 209 of thecannula 201 in order to anchor the apparatus 200 within the bone andinhibit relative movement of the apparatus 200 and bone.

In one embodiment shown in FIG. 2D, the anchoring device 227 comprises aplurality of wires 229 that extend from the tip end 209 of the outercannula 201. The wires 229 may extend into the relatively softer (i.e.,cancellous) bone tissue in the interior of the patient's bone to anchorthe apparatus 200 within the bone. Although the embodiment shown in FIG.2D illustrates two wires 229 extending from the outer cannula 201, itwill be understood that an anchoring device 227 may include a differentnumber of wires 229. Further, as an alternative and/or in addition towires 229 as shown in FIG. 2D, the anchoring device 227 may comprise oneor more of a burr, a cleat, and expandable cage or other member thatextends from the cannula 201 to help anchor the apparatus 200 within thepatient's bone.

The anchoring device 227 is preferably comprised of a bio-compatiblematerial, such as a nickel-titanium (nitinol) alloy. In someembodiments, the anchoring device 227 may be composed of a shape memoryalloy, such as nitinol, and may be manufactured to a body temperatureresponse so that the anchoring device 227 assumes a pre-determinedaustenitic shape within the patient's body. The pre-determinedaustenitic shape may be configured to aid in the anchoring of theapparatus 200 when the apparatus 200 is inserted into the patient'sbone.

In some embodiments, the anchoring device 227, such as wires 229, may belocated on or within the outer cannula 201 of the apparatus 200. Forexample, the anchoring device 227 (e.g., wires 229) may be attached tothe outer surface of the cannula 201 and may extend out from the cannula201 when the cannula 201 is inserted into a bone. In furtherembodiments, the anchoring device 227 (e.g., wires 229) may be locatedwithin the cannula, such as within the central opening 203 of thecannula 201 or within one more housings formed within the sidewall ofthe cannula 201. The anchoring device 227 may be deployed by pushing theanchoring device 227 (e.g. wires 229) out through the tip end 209 of thecannula 201 such that the anchoring device 227 may extend into thesurrounding bone tissue.

In some embodiments, the anchoring device 227 may be deployed using amechanical actuator, such as a button, a rotatable handle or knob, or amechanical slide, that is coupled to the anchoring device 227 andenables a user to cause the anchoring device 227 to extend into thesurrounding bone tissue. The mechanical actuator may be a spring-loadedactuator that causes the anchoring device 227 (e.g., wires 229) toproject out from the tip end 209 of the cannula 201 and into thesurrounding tissue. In some embodiments, the anchoring device 227 maydeploy automatically when the marker device 219 is inserted within theouter cannula 201. For example, the marker device 219 may includefeature(s) that engage with and push down on the anchoring device 227 asthe marker device 219 is inserted, causing the anchoring device 217 toextend out from the tip end 209 of the outer cannula 201. In someembodiments, inserting the marker device 219 may engage a triggeringdevice (e.g., a spring-loaded actuator) that causes the anchoring device217 to extend out from the outer cannula 201. The apparatus 200 may beconfigured such that the insertion of a different component into theouter cannula 201, such as the elongated member 205 of FIGS. 2A-2B, doesnot cause the anchoring device 227 to deploy.

In some embodiments, the anchoring device 227 (e.g., wires 229) may belocated on the marker device 219, such as attached to the elongatedmember 225 shown in FIGS. 2C and 2D. Fully inserting the elongatedmember 225 into the outer cannula 201 may cause the anchoring device 227to project out through the tip end 209 of the cannula 201 and extendinto the surrounding bone tissue.

In embodiments, the anchoring device 227 may be retracted from thesurrounding tissue before the apparatus 200 is removed from the patient.For example, the anchoring device 227 (e.g., wires 229) may be pulledinto the outer cannula 201 using a mechanical actuator, or automaticallyby removing the marker device 219 from the cannula 201.

FIG. 4 illustrates another embodiment apparatus 400 for attaching areference marker to a patient. Apparatus 400 is similar to apparatus 200and includes an elongated member 401 (e.g., a rod) having a sharp tip407 at a first end 409 of the apparatus 400. A handle 415 (e.g., at-handle) may be located at a second end 413 of the apparatus 400. Amarker device 419 is attached to the elongated member 401 near thesecond end 413 of the apparatus. The elongated member 401 may be ahollow cannula such as described above in reference to FIGS. 2A-2D, ormay be a solid or partially solid rod that does not include a centralopening extending through the elongated member 401. The marker device419, handle 413 and/or sharp tip 407 may be non-removably attached tothe elongated member 401.

The apparatus 400 may be inserted into a patient such that the sharp tip407 pierces the skin and punctures the cortical surface of an underlyingbone (e.g., the iliac crest). In embodiments, the user may continue toadvance the sharp tip 407 into the interior portion of the bone toattach the apparatus 400 to the patient. Alternately, after puncturingthe cortical surface, the sharp tip 407 may be retracted into theelongated member 401 (e.g., retracted into a housing located near thefirst end 409 of the elongated member 401, or pulled out through acentral opening in the elongated member 401 similarly to the apparatus200 described above). The elongated member 401 may be advanced into theinterior of the bone with the sharp tip 407 removed or retracted. Theapparatus 400 may optionally also include an anchoring device 427 (e.g.,a plurality of wires 429, shown in phantom in FIG. 4) that may bedeployed to anchor the apparatus 400 within the patient's bone. Theanchoring device 427 may be selectively deployed using a triggermechanism (e.g., a button 428).

Further embodiments include systems for performing image guided surgerythat include multiple reference markers attached to a patient. Attachingmultiple reference marker devices to the patient may provide redundancysuch that if one marker device is not rigidly secured or becomes loose,any loss in the accuracy of the surgical navigation may be compensatedfor by one or more additional marker devices. The multiple markerdevices may also be used to verify the accuracy of the patientregistration, and in some cases, may enable a registration correction tobe performed without needing to re-scan the patient using an imagingdevice.

FIG. 5 illustrates an embodiment system 500 for performing image guidedsurgery (IGS) that includes two reference markers 501, 503 attached to apatient 502. The two reference markers 501, 503 may each comprise anapparatus 200, 400 such as described above in connection with FIGS.2A-4, and may be embedded within different bone structures of thepatient 502 (e.g., the left and right iliac crests). Although tworeference markers 501, 503 are shown in FIG. 5, it will be understoodthat a greater number (e.g., 3, 4, 5, etc.) of reference markers may beutilized.

During image guided surgery, representations of tracked objects may bedisplayed in conjunction with diagnostic images obtained using animaging device 103 (e.g., a CT scanner) in a patient-based coordinatesystem that may be based on the location(s) of reference marker 501and/or reference marker 503. In some embodiments, the patient-basedcoordinate system may be a blended or interpolated reference coordinatesystem that may be weighted by distance from the first and secondreference marker devices 501, 503. Various embodiments for performingimage guided surgery using multiple reference markers attached to thepatient are described in U.S. Provisional Application No. 62/385,552,filed Sep. 9, 2016 (Attorney Docket No. GYS-2P), the entire contents ofwhich are incorporated herein by reference.

The reference markers 501, 503 may be tracked by the motion trackingsystem 105 to detect a relative motion of reference markers 501, 503during a surgical procedure. A detected relative motion between themarkers may indicate that a reference marker 501, 503 is loose and/orhas accidentally been bumped causing it to change its position relativeto the patient during a surgical procedure. In such a case, the imagesdisplayed by the image guided surgery system may no longer accuratelyrepresent the current patient situation. In embodiments, the user may benotified (e.g., via an audible and/or visual alert) when there is adetected relative motion (e.g., greater than a pre-determined magnitude)between reference markers 501, 503. In some embodiments, the IGSsoftware may be configured to determine which of the reference markers501, 503 most likely moved relative to the patient (for example, where afirst reference marker abruptly changes its position/orientation withrespect to the camera position while a second marker'sposition/orientation with respect to the camera(s) remains constant, itis significantly more likely that the first marker has moved). Inresponse to determining that a first reference marker has moved relativeto the patient, the IGS may automatically perform surgical navigationwithin a coordinate system based on the location of the second markerdevice.

FIG. 6 illustrates a further embodiment system 600 for performing imageguided surgery (IGS) that includes two reference markers 601, 603attached to a patient 602. The two reference markers 601, 603 may be ofdifferent types and/or use different mechanisms for attaching to thepatient. A first reference marker 601 may comprise an apparatus 200, 400such as described above in connection with FIGS. 2A-4, and may beembedded within a first bone structure of the patient 602 (e.g., theiliac crest). One or more additional reference markers 603 may beattached to a different portion of the patient's skeletal structure,such as to a vertebra of the patient. The additional reference marker603 may include a bone clamp that attaches to the spinous process, forexample. The system 600 may otherwise be similar to system 500 asdescribed above.

FIG. 7 illustrates yet another embodiment system 700 for performingimage guided surgery (IGS). In this embodiments, a reference marker 701may comprise an apparatus 200, 400 such as described above in connectionwith FIGS. 2A-4, and may be embedded within a first bone structure ofthe patient 702 (e.g., the iliac crest). A plurality of optical markers703 (e.g., reflective spheres) may be attached over the skin surface ofthe patient 702. The optical markers 703 may be attached using anadhesive. The plurality of optical markers 703 may at least partiallysurround the surgical area.

Reference marker 701 may be rigidly fixed to the patient's bone, whilethe additional optical markers 703 in this embodiment are attached tosoft tissue of the patient and may have a limited degree of motion(e.g., both absolute motion relative to the anatomic region of interestand relative motion with respect to the other markers 703). Imageregistration and surgical navigation may utilize a patient-basedcoordinate system that may be based on the tracked position andorientation of the rigidly-attached reference marker 701. The additionaloptical markers 703 may also be tracked and may be used to verify thatreference marker 701 has not moved with respect to the patient 702. Forexample, an average of the tracked positions of the additional opticalmarkers 703 may be compared to the tracked position of reference marker701. Where the reference marker 703 is determined to have moved in aparticular direction and/or by a particular magnitude with respect tothe average position of markers 703, this may indicate that thereference marker 701 has moved relative to the patient 702. The user maybe notified (e.g., via an audible and/or visual alert) when it isdetermined that the reference marker 701 has moved.

The foregoing method descriptions are provided merely as illustrativeexamples and are not intended to require or imply that the steps of thevarious embodiments must be performed in the order presented. As will beappreciated by one of skill in the art the order of steps in theforegoing embodiments may be performed in any order. Words such as“thereafter,” “then,” “next,” etc. are not necessarily intended to limitthe order of the steps; these words may be used to guide the readerthrough the description of the methods. Further, any reference to claimelements in the singular, for example, using the articles “a,” “an” or“the” is not to be construed as limiting the element to the singular.

The preceding description of the disclosed aspects is provided to enableany person skilled in the art to make or use the present invention.Various modifications to these aspects will be readily apparent to thoseskilled in the art, and the generic principles defined herein may beapplied to other aspects without departing from the scope of theinvention. Thus, the present invention is not intended to be limited tothe aspects shown herein but is to be accorded the widest scopeconsistent with the principles and novel features disclosed herein.

What is claimed is:
 1. An apparatus for attaching a reference marker toa patient, comprising: an elongated member extending between a first endand a second end; a sharp tip located proximate to the first end of theelongated member that is configured to break through a cortical surfaceof a bone of the patient to enable the elongated member to be advancedinto the bone; an anchoring device that is extendable from the elongatedmember in order to anchor the apparatus within the bone and inhibitrelative movement of the apparatus and the bone; and a reference markerdevice comprising at least one optical marker configured to enable theapparatus to be tracked using a motion tracking system.
 2. The apparatusof claim 1, wherein the elongated member comprises a cannula having acentral opening extending between the first end and the second end ofthe cannula.
 3. The apparatus of claim 1, further comprising a secondelongated member having a first end and a second end, the sharp tipbeing located at the first end of the elongated member, the secondelongated member being insertable into the cannula such that the sharptip extends beyond the first end of the cannula.
 4. The apparatus ofclaim 3, further comprising a connector for connecting the cannula andthe second elongated member at their respective second ends.
 5. Theapparatus of claim 3, wherein the second elongated member is removablefrom the cannula.
 6. The apparatus of claim 5, wherein the secondelongated member is removable from the cannula after the sharp tipbreaks through the cortical surface, and the cannula is configuredcollect bone tissue within the central opening of the cannula when thecannula is advanced into an interior portion of the bone.
 7. Theapparatus of claim 6, wherein the bone tissue is removable through thesecond end of the cannula to harvest bone marrow of the patient.
 8. Theapparatus of claim 5, further comprising: a third elongated member thatis insertable into the cannula, the marker device being attached to thethird elongated member.
 9. The apparatus of claim 8, wherein theanchoring device deploys automatically when the third elongated memberis inserted into the cannula.
 10. The apparatus of claim 8, furthercomprising an attachment mechanism that is configured to lock the thirdelongated member within the cannula.
 11. The apparatus of claim 1,wherein the anchoring device is deployed by extending a plurality ofanchoring elements radially outward with respect to an outer surface ofthe elongated member and/or longitudinally away from the first end ofthe elongated member.
 12. The apparatus of claim 11, wherein theplurality of anchoring elements comprise a plurality of wires that areextendable from the first end of the elongated member.
 13. The apparatusof claim 11, wherein the anchoring device is composed of a shape-memoryalloy.
 14. The apparatus of claim 11, wherein the anchoring devicecomprises a nickel titanium alloy.
 15. The apparatus of claim 11,further comprising an actuator for selectively deploying the anchoringdevice.
 16. The apparatus of claim 1, wherein the bone is an iliac crestof the patient.
 17. The apparatus of claim 1, wherein the referencemarker device is non-removably attached to the elongated member.
 18. Theapparatus of claim 1, wherein the at least one optical marker comprisesa plurality of reflective spheres mounted to a rigid frame.
 19. A methodof performing image guided surgery, comprising: inserting an apparatuscomprising an elongated member having a sharp tip at an end of theelongated member into the body of a patient to cause the sharp tip tobreak through a cortical surface of a bone of the patient; anchoring theapparatus within the bone to inhibit relative movement of the apparatusand the bone; and tracking a reference marker device having at least oneoptical marker attached to the apparatus using a motion tracking system.20. A system for performing image guided surgery, comprising: a motiontracking system comprising at least one optical sensing device; aplurality of reference marker devices attached to a patient, wherein atleast a first reference marker device is attached using an apparatus asrecited in claim
 1. 21. The system of claim 20, wherein the firstreference marker device is attached to an iliac crest of the patient.22. The system of claim 21, wherein a second reference marker device isattached using an apparatus as recited in claim
 1. 23. The system ofclaim 22, wherein the second reference marker device is attached to aniliac crest of the patient.
 24. The system of claim 21, wherein a secondreference marker device is attached to a vertebra of the patient. 25.The system of claim 21, wherein a second reference marker devicecomprises a plurality of optical markers attached over the skin surfaceof the patient.
 26. The system of claim 20, wherein the system furthercomprises a processing system coupled to the motion tracking system thatdetermines whether the first reference marker device has moved relativeto the patient by detecting a relative movement between the firstreference marker device and at least one second reference marker deviceattached to the patient.